U.S. patent number 7,669,989 [Application Number 11/502,419] was granted by the patent office on 2010-03-02 for liquid application device and inkjet recording apparatus.
This patent grant is currently assigned to Canon Kabushiki Kaisha. Invention is credited to Osamu Iwasaki, Atsuhiko Masuyama, Yoshinori Nakagawa, Naomi Oshio, Naoji Otsuka.
United States Patent |
7,669,989 |
Oshio , et al. |
March 2, 2010 |
Liquid application device and inkjet recording apparatus
Abstract
A liquid application device and an inkjet recording apparatus
are capable of reducing nonuniformity in application of liquid onto
a recording medium, and thereby forming high-quality images on a
steady basis. In the present invention, information indicating the
lapse of time after the previous circulation operation is obtained.
Subsequently, based on the obtained information indicating the
lapse of time, a preliminary circulation sequence is determined.
Finally, the preliminary circulation sequence is performed based on
the determined preliminary circulation sequence.
Inventors: |
Oshio; Naomi (Kawasaki,
JP), Otsuka; Naoji (Yokohama, JP), Iwasaki;
Osamu (Tokyo, JP), Nakagawa; Yoshinori (Kawasaki,
JP), Masuyama; Atsuhiko (Tokyo, JP) |
Assignee: |
Canon Kabushiki Kaisha (Tokyo,
JP)
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Family
ID: |
37736688 |
Appl.
No.: |
11/502,419 |
Filed: |
August 11, 2006 |
Prior Publication Data
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Document
Identifier |
Publication Date |
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US 20070035592 A1 |
Feb 15, 2007 |
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Foreign Application Priority Data
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Aug 15, 2005 [JP] |
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2005-235403 |
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Current U.S.
Class: |
347/84 |
Current CPC
Class: |
B41J
11/0015 (20130101) |
Current International
Class: |
B41J
2/175 (20060101) |
Field of
Search: |
;347/84,85,103 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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8-58069 |
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Mar 1996 |
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JP |
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8-72227 |
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Mar 1996 |
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JP |
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2001-70858 |
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Mar 2001 |
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JP |
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2002-517341 |
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Jun 2002 |
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JP |
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Primary Examiner: Do; An H
Attorney, Agent or Firm: Fitzpatrick, Cella, Harper &
Scinto
Claims
What is claimed is:
1. A liquid application device comprising: a liquid application
unit including an application member for applying liquid to a
medium and a retention member for retaining the liquid in a liquid
retention space formed in contact with the application member,
wherein the liquid application unit applies the liquid retained in
the liquid retention space to the medium via the application member
by rotating the application member; a storage unit configured to
store the liquid; a passage configured to cause the storage means
and the retention member to communicate with each other; a
circulating unit configured to control a circulation operation for
circulating the liquid in a channel including the storage unit, the
passage, and the liquid retention space; and an obtaining unit
configured to obtain information concerning lapse of time after a
previous circulation operation by the circulating unit, wherein the
circulating unit controls the circulation operation according to
the information obtained by the obtaining unit.
2. The liquid application device according to claim 1, wherein,
based on the information obtained by the obtaining unit, the
circulating unit selects one circulation operation to be executed
from a plurality of different circulation operations in which at
least one of a circulation speed of the liquid and a circulation
period of the liquid is different.
3. The liquid application device according to claim 1, further
comprising a determination unit configured to determine the amount
of the liquid necessary for the circulation operation, wherein the
circulating unit controls the circulation operation depending on
the amount determined by the determination unit.
4. The liquid application device according to claim 1, wherein the
circulating unit includes a pump which generates a flow of the
liquid in the channel.
5. A liquid application device comprising: a liquid application
unit including an application member for applying liquid to a
medium and a retention member for retaining the liquid in a liquid
retention space formed in contact with the application member,
wherein the liquid application unit applies the liquid retained in
the liquid retention space to the medium via the application member
by rotating the application member; a storage unit configured to
store the liquid; a passage configured to cause the storage unit
and the retention member to communicate with each other; and a
circulating unit configured to execute a circulation operation for
circulating the liquid in a channel including the storage unit, the
passage, and the liquid retention space, wherein the circulating
unit increases a circulation period of a subsequent circulation
operation, as a lapse of time after a previous circulation
operation increases.
6. An inkjet recording apparatus comprising: the liquid application
device according to claim 1; and a recording unit configured to
record an image on the medium by ejecting ink from a recording head
to the medium to which the liquid has been applied by the liquid
application device.
7. The inkjet recording apparatus according to claim 6, wherein the
liquid includes a component which reacts with the ink.
8. A liquid application device comprising: a liquid application
unit including an application member for applying liquid to a
medium and a retention member for retaining the liquid in a liquid
retention space formed in contact with the application member,
wherein the liquid application unit applies the liquid retained in
the liquid retention space to the medium via the application member
by rotating the application member; a storage unit configured to
store the liquid; a passage configured to cause the storage means
and the retention member to communicate with each other; and a
circulating unit configured to execute a circulation operation for
circulating the liquid in a channel including the storage unit, the
passage, and the liquid retention space, wherein the circulating
unit increases a circulation speed of a subsequent circulation
operation as a lapse of time after a previous circulation operation
increases.
9. An inkjet recording apparatus comprising: a liquid application
unit including an application roller for applying a liquid which
reacts with an ink to a medium and a retention member for retaining
the liquid in a liquid retention space formed in contact with the
application member, wherein the liquid application unit applies the
liquid retained in the liquid retention space to the medium via the
application member by rotating the application roller; a recording
head configured to eject the ink to the medium to which the liquid
has been applied by the liquid application unit; a storage unit
configured to store the liquid; a passage configured to cause the
storage unit and the retention member to communicate with each
other; a circulating unit configured to control a circulation
operation for circulating the liquid in a channel including the
storage unit, the passage, and the liquid retention space; and an
obtaining unit configured to obtain information concerning a lapse
of time after a previous circulation operation by the circulating
unit, wherein the circulating unit controls at least one of a
circulation speed and a circulation period of the circulation
operation according to the information obtained by the obtaining
unit.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a liquid application device and an
inkjet recording apparatus, and particularly to a liquid
application device for applying liquid to a medium for a certain
purpose which is, for example, to promote the coagulation of
pigment when recording is carried out using an ink which contains
the pigment as a coloring material. The present invention also
relates particularly to an inkjet recording apparatus which
includes a mechanism for applying liquid to a recording medium used
in inkjet recording, for a purpose which is, for example, to
promote the coagulation of pigment when recording is carried out
using an ink containing the pigment as a coloring material.
2. Description of the Related Art
As modes of widely applying liquid or liquid material to a medium,
spin coaters, roll coaters, bar coaters, and die coaters are known.
These application modes are adopted on the assumption that the
application is consecutively performed to a relatively long
application medium. As a result, when application media with a
relatively small size are intermittently fed, and the application
is performed to these media, the problem can occur that a uniform
coating film cannot be obtained due to the irregularities of beads
of coating material at the start or the end point of the
application, for example.
As a configuration capable of solving such a problem, one which is
described in Japanese Patent Application Laid-open No. 2001-070858
is known. This is a die-coater type, in which a rotating rod bar is
used, and coating material is discharged from a discharging slit to
the rod bar to form a coating film on the rod bar. The formed
coating film is brought into contact with an application medium and
is transferred thereto as the rod bar rotates. When the coating
film formed on the rod bar is not transferred or applied to an
application medium, the coating material returns into the head as
the rod bar rotates, and the material is collected via a collection
slit. In other words, even when the application is not carried out,
the rod bar keeps rotating, and the coating material remains
forming a coating film on the rod bar. In this way, it is made
possible to obtain a uniform coating film even when the application
media are intermittently supplied, and the application is
intermittently performed thereto.
Among inkjet recording apparatuses, one which utilizes a liquid
application mechanism is known. According to the description in
Japanese Patent Application Laid-open No. 2002-517341, a doctor
blade abutting a roller is used, coating liquid is stored between
the blade and the roller, and the coating liquid is applied to the
roller as the roller rotates. As the roller rotates, the applied
coating liquid is transferred or applied to a base material
transferred between this roller and another roller. Also in
Japanese Patent Application Laid-open No. 8-072227 (1996), shown is
a mechanism which previously applies a treatment liquid
insolubilizing dyes before recording, in an inkjet recording
apparatus. The description of the first example in this document
discloses that the treatment liquid in a replenishing tank adheres
to a rotating roller and is thus pumped, and, at the same time, the
pumped treatment liquid is applied to a recording paper.
However, with regard to the configurations described in the above
documents, Japanese Patent Application Laid-open No. 2001-70858,
Japanese Patent Application Laid-open No. 2002-517341 and Japanese
Patent Application Laid-open No. 8-72227 (1996), the rod bar or the
roller rotates, and the application liquid is applied or supplied
to the surface of the bar or the roller, in which the area where
the application or supply is performed, is opened to or
communicates with the atmosphere. For this reason, there arises the
problem of vaporization of the application liquid. In addition,
there is a possibility that the problem can occur that, when the
position of the apparatus changes, this results in the leakage of
the application liquid.
Among others, with regard to the inkjet recording apparatuses, such
as printers, with the leakage of the liquid due to the position
change at the time of carrying taken into consideration, it is
difficult to apply the application mechanism described in the above
documents to downsized apparatuses.
Meanwhile, in Japanese Patent Application Laid-open No. 8-058069
(1996), disclosed is a gravure printing machine having a
configuration in which the area is sealed off where ink as the
application liquid is applied or supplied to a roller which has a
print pattern formed on the surface thereof. With regard to this
apparatus, an ink chamber having two doctor blades is brought into
contact with the circumferential surface of the roller to form a
liquid room (an ink reservoir) between the chamber and the
roller.
In the apparatus described in Japanese Patent Application Laid-open
No. 8-58069 (1996), a pump is provided between an ink tank to store
ink and the liquid room. The ink in the ink tank is pumped into the
liquid room by the pump, so that the ink is supplied from the ink
tank to the liquid room. In addition, the ink in the liquid room is
sent to a receiving tank which receives the ink discharged from the
liquid room.
In that occasion, in a case where the apparatus has been stopped
for a long time period, thickening or sticking of the application
liquid due to vaporization and precipitation thereof sometimes
occurs in the ink room and in a flow channel for sending ink to the
ink room. However, with respect to this problem of thickening and
sticking of the application liquid in the flow channel, there is no
mention in Japanese Patent Application Laid-open No. H08-58069
A.
In a case where the application liquid has vaporized in the channel
and thereby has thickened or stuck therein, circulation of the
application liquid is sometimes hindered. As a result it is
sometimes made difficult to perform favorable circulation to the
extent that reliability of the application device can be
maintained. For example, when the thickening has occurred in the
ink room, viscosity of the liquid to be applied has become higher
than usual. In a case where an adequate application has been
hindered thereby, partial nonuniformity in the application is
sometimes generated. There is concern that this nonuniformity
adversely affects the image to be printed eventually such as
mottling.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a liquid
application device and an inkjet recording apparatus, which are
capable of reducing nonuniform application of liquid to a
medium.
In first aspect of the present invention, a liquid application
device comprises: liquid application means including an application
member for applying liquid to a medium, and a retention member for
retaining the liquid in a liquid retention space formed in contact
with the application member, wherein the liquid application means
applies the liquid retained in the liquid retention space to the
medium via the application member by rotating the application
member; storage unit for storing the liquid; passage which cause
the storage means and the retention member to communicate with each
other; circulating means for circulating the liquid in a channel
including the storage unit, the passage, and the liquid retention
space; obtaining means for obtaining information concerning lapse
of time after the previous circulation operation by the circulating
means; wherein, the circulating means controls a circulation
operation according to the information obtained by the obtaining
means.
In second aspect of the present invention, a liquid application
device comprises: liquid application means including an application
member for applying liquid to a medium, and a retention member for
retaining the liquid in a liquid retention space formed in contact
with the application member, wherein the liquid application means
applies the liquid retained in the liquid retention space to the
medium via the application member by rotating the application
member; storage unit for storing the liquid; passage which cause
the storage means and the retention member to communicate with each
other; and circulating means for circulating the liquid in a
channel including the storage unit, the passage, and the liquid
retention space; wherein, the circulating means make a circulation
speed of the current circulation operation faster, or a circulation
period of the current circulation operation longer, as lapse of
time after the previous circulation operation takes longer.
In third aspect of the present invention, a liquid application
device comprises: liquid application means including an application
member for applying the liquid to a medium, and a retention member
for retaining the liquid in a liquid retention space formed in
contact with the application member, wherein the liquid application
means applies the liquid retained in the liquid retention space to
the medium via the application member by rotating the application
member; storage unit for storing the liquid; passage which cause
the storage means and the retention member to communicate with each
other; circulating means for circulating the liquid in a channel
including the storage unit, the passage, and the liquid retention
space; memory means for storing first information concerning a
finish of a circulation operation by the circulating means; first
obtaining means for, based on the first information stored in the
memory means, obtaining second information concerning lapse of time
after the previous circulation operation; and second obtaining
means for, based on a data which associates the lapse of time with
the circulation operation, obtaining third information concerning
the circulation operation corresponding to the second information;
wherein, the circulating means controls the current circulation
operation according to the third information obtained by the second
obtaining means.
In fourth aspect of the present invention, an inkjet recording
apparatus comprises: the liquid application device according to the
first aspect of the present invention; and recording means for
recording an image on a medium by ejecting ink from a recording
head to the medium to which the liquid has been applied by the
liquid application device.
In fifth aspect of the present invention, a recording apparatus
comprises: the liquid application device according to claim 1; and
recording means for recording an image on a medium by applying a
recording agent to the medium to which the liquid has been applied
by the liquid application device.
In sixth aspect of the present invention, a method of controlling a
liquid application device, comprises: a step of preparing the
liquid application device including an application member for
applying the liquid to the medium, and a retention member for
retaining the liquid in a liquid retention space formed in contact
with the application member, wherein liquid application device
applies the liquid retained in the liquid retention space to the
medium via the application member by rotating the application
member; a first step of circulating the liquid in a channel
including a storage means for storing the liquid, passage, and the
liquid retention space, the passage causing the storage means, and
the retention member to communicate with each other; a second step
of obtaining information concerning a lapse of time after a finish
of the first step; and a third step of circulating the liquid in
the channel depending on the information obtained in the second
step.
According to the present invention, a circulation operation is
controlled on liquid in accordance with the lapse of time after the
previous circulation operation. In so doing, the circulation
operation is executable as being suitable for the degree of
vaporization of the liquid, the degree varying depending upon the
lapse of time. As a result, the thickening and/or the sticking of
the liquid in the channel are reduced, and it becomes possible to
reduce nonuniformity in the application derived from these
thickening and/or sticking.
Further features of the present invention will become apparent from
the following description of exemplary embodiments (with reference
to the attached drawings).
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a perspective view showing an overall construction of an
embodiment of a liquid application device of the present
invention;
FIG. 2 is a longitudinal sectional side view showing an example of
an arrangement of elements including an application roller, a
counter roller and a liquid retention member;
FIG. 3 is a front view of the liquid retention member shown in
FIGS. 1 and 2;
FIG. 4 is an end view showing an end obtained by cutting the liquid
retention member shown in FIG. 3 along the line IV-IV;
FIG. 5 is an end view showing an end obtained by cutting the liquid
retention member shown in FIG. 3 along the line V-V;
FIG. 6 is a plan view of the liquid retention member shown in FIG.
3;
FIG. 7 is a left side view showing a state where a contact portion
of the liquid retention member shown in FIG. 3 is allowed to abut
on the liquid application roller;
FIG. 8 is a right side view showing a state where the contact
portion of the liquid retention member shown in FIG. 3 is allowed
to abut on the liquid application roller;
FIG. 9 is a longitudinal sectional view showing a state where a
liquid retention space created by the liquid retention member and
the application roller is filled with an application liquid, and
the liquid is applied to an application medium as the application
roller rotates in the embodiment of the present invention;
FIG. 10 is a longitudinal sectional view showing a state where the
liquid retention space created by the liquid retention member and
the application roller is filled with the application liquid, and
the application roller is rotated with no application medium
present in the embodiment of the present invention;
FIG. 11 is a diagram showing a schematic configuration of a liquid
channel of the liquid application device in the embodiment of the
present invention;
FIG. 12 is a block diagram showing a schematic configuration of a
control system in the embodiment of the present invention;
FIG. 13 is a flow chart showing a liquid-application operation
sequence in the embodiment of the present invention;
FIG. 14 is a flow chart showing the processing of a preliminary
circulation operation according to the embodiment of the present
invention;
FIG. 15 is a diagram showing a table, by which a preliminary
circulation sequence is determined, according to the embodiment of
the present invention;
FIG. 16 is a diagram showing a table, by which contents of the
preliminary circulation sequence are determined, according to the
embodiment of the present invention;
FIG. 17 is a flow chart showing the processing of the preliminary
circulation operation according to the embodiment of the present
invention;
FIG. 18 is a diagram showing tables, by which the preliminary
circulation sequence is determined, according to the embodiment of
the present invention;
FIG. 19 is a diagram for explaining an operation of a pump in the
embodiment of the present invention;
FIG. 20 is a longitudinal sectional side view showing a schematic
configuration of an inkjet recording apparatus in an embodiment of
the present invention;
FIG. 21 is a perspective view showing a main part of the inkjet
recording apparatus shown in FIG. 20;
FIGS. 22 and 23 are diagrams for explaining a three-way valve in
the embodiment of the present invention;
FIGS. 24 to 26 are explanatory diagrams for explaining an
application process proceeding between an application surface and a
surface of a medium, in a case where the medium P is a plain
paper;
FIG. 27 is a block diagram showing a schematic configuration of a
control system of the inkjet recording apparatus according to the
embodiment of the present invention; and
FIG. 28 is a flow chart showing a sequence of a recording operation
in the inkjet recording apparatus in still another embodiment of
the present invention.
DESCRIPTION OF THE EMBODIMENTS
Detailed description will be given below of a preferred embodiment
of the present invention with reference to the accompanying
drawings.
First Embodiment
FIG. 1 is a perspective view showing an overall structure of the
embodiment of a liquid application device 100 of the present
invention. The liquid application device 100 shown here generally
includes liquid application means for applying a predetermined
application liquid to a medium (hereinafter also referred to as the
application medium) which is an object to which the liquid is
applied and liquid supply means for supplying the application
liquid to the liquid application means.
The liquid application means includes a cylindrical application
roller 1001, a cylindrical counter roller (a medium supporting
member) 1002 placed so as to face the application roller 1001 and a
roller drive mechanism 1003 driving the application roller 1001.
The roller drive mechanism 1003 includes a roller drive motor 1004
and a power transmission mechanism 1005 including a gear train for
transmitting the driving force of the roller drive motor 1004 to
the application roller 1001.
The liquid supply means includes a liquid retention member 2001
retaining the application liquid between itself and a
circumferential surface of the application roller 1001, and a
liquid channel 3000 (not shown in FIG. 1), to be described later,
supplying the liquid to the liquid retention member 2001. The
application roller 1001 and the counter roller 1002 are freely
rotatably supported individually by parallel shafts, each of which
has both ends thereof freely rotatably fitted to a frame (not
shown). The liquid retention member 2001 extends substantially over
the entire length of the application roller 1001, and is movably
mounted to the frame via a mechanism which enables the liquid
retention member 2001 to come into contact with or to separate from
the circumferential surface of the application roller 1001.
The liquid application device of this embodiment further includes
an application medium feeding mechanism 1006 for transferring the
application medium to a nip area between the application roller
1001 and the counter roller 1002, the application medium feeding
mechanism 1006 being constituted of a pickup roller and other
elements. In a transfer path of the application media, a sheet
discharging mechanism 1007 transferring, to a sheet discharging
unit (not shown), the application medium to which the application
liquid has been applied is provided downstream of the application
roller 1001 and the counter roller 1002, the sheet discharging
mechanism 1007 having a sheet discharging roller and other
elements. As in the case of the application roller and the like,
these paper feeding mechanism and the sheet discharging mechanism
are operated by the driving force of the drive motor 1004
transmitted via the power transmission mechanism 1005.
It should be noted that the application liquid used in this
embodiment is a liquid used for the purpose of advancing the start
of the coagulation of pigment when recording is carried out using
an ink which contains pigment as a coloring material.
An example of components of the application liquid is described
below.
TABLE-US-00001 calcium nitrate tetrahydrate 10% glycerin 42%
surface-active agent 1% water the rest
The viscosity of the application liquid is from 5 to 6 cP
(centipoises) at 25.degree. C.
Needless to say, in application of the present invention, the
application liquid is not limited to the above liquid. As another
application liquid, for example, a liquid which contains a
component insolubilizing the dye or causing the coagulation of the
dye, can be used. As yet another application liquid, a liquid which
contains a component suppressing curling of the application media
(the phenomenon that the media take a curved shape), can be
used.
In a case where water is used in the applied liquid, the sliding
property at the contact area of the liquid retention member with
the application roller of the present invention will be improved by
mixing a component reducing the surface tension with the liquid. In
the above example of the components of the applied liquid, glycerin
and the surface-active agent are the components reducing the
surface tension of water.
More detailed description will now be given of construction of each
portion.
FIG. 2 is an explanatory longitudinal sectional side view showing
an example of an arrangement of elements including the application
roller 1001, the counter roller 1002 and the liquid retention
member 2001.
The counter roller 1002 is biased toward the circumferential
surface of the application roller 1001 by bias means (not shown),
and rotates the application roller 1001 clockwise in the figure.
This rotation makes it possible to hold, between both rollers, the
application medium P to which the application liquid is applied,
and to transfer the application medium P in the direction indicated
by the arrow in the figure.
The liquid retention member 2001 is designed to create an elongated
liquid retention space S extending across a liquid application
region of the application roller 1001 while the liquid retention
member 2001 abuts on the circumferential surface of the application
roller 1001, biased thereto by the bias force of a spring member
(pressing means) 2006. The application liquid is supplied from the
below-described liquid channel 3000 into the liquid retention space
S through the liquid retention member 2001. In this case, since the
liquid retention member 2001 is constructed as described below, it
is possible to prevent the application liquid from accidentally
leaking out of the liquid retention space S while the application
roller 1001 is stopped.
A construction of the liquid retention member 2001 is shown in
FIGS. 3 to 8.
As shown in FIG. 3, the liquid retention member 2001 includes a
space creating base 2002 and an annular contact member 2009
provided on one surface of the space creating base 2002 in a
protruding manner. In the space creating base 2002, a concave
portion 2003, a bottom portion of which has a circular-arc cross
section, is formed in the middle thereof along the longitudinal
direction. Each straight portion of the contact member 2009 is
fixedly attached to the space creating base 2002 along the edge
portion of the concave portion 2003, and each circumferential
portion thereof is fixedly attached to the space creating base 2002
so as to run from one edge portion to the other edge portion via
the bottom portion. In this way, when abutting on the application
roller 1001, the contact member 2009 of the liquid retention member
2001 can abut thereon in conformity with the shape of the
circumferential surface of the application roller, which realizes
the abutting with a uniform pressure.
As described above, with regard to the liquid retention member in
this embodiment, the seamless contact member 2009 formed in one
body is caused to abut on the outer circumferential surface of the
application roller 1001 consecutively with no space therebetween by
the bias force of the spring member 2006. As a result, the liquid
retention space S becomes a substantially closed space defined by
the contact member 2009, one surface of the space creating base and
the outer circumferential surface of the application roller 1001,
and the liquid is retained in this space. Thus, while the rotation
of the application roller 1001 is stopped, the contact member 2009
and the outer circumferential surface of the application roller
1001 can keep a fluid-tight state, and can surely prevent the
liquid from leaking out. On the other hand, when the application
roller 1001 rotates, as described later, the application liquid
goes past the contact member 2009 in such a manner as to pass
through the interface between the outer circumferential surface of
the application roller 1001 and the contact member 2009 and adheres
to the outer circumferential surface of the application roller like
layer. "While the application roller 1001 is stopped, the outer
circumferential surface thereof and the contact member 2009 are in
a fluid-tight state" means that, as described above, the liquid is
not allowed to pass through the boundary between the inside and the
outside of the space. In this case, the abutting condition of the
contact member 2009 includes a condition where the contact member
2009 abuts on the outer circumferential surface of the application
roller 1001 with a film of the liquid, which is formed by the
capillary action, interposed therebetween, as well as a condition
where the contact member 2009 directly abuts on the outer
circumferential surface of the application roller 1001.
The left and right end portions of the contact member 2009 in the
longitudinal direction have a gently curved shape when viewed from
any one of the front thereof (FIG. 3), the top thereof (FIG. 6),
and a side thereof (FIGS. 7 and 8), as shown in FIGS. 3 to 8. As a
result, even when the contact member 2009 is allowed to abut on the
application roller 1001 with a relatively high pressure, the whole
contact member 2009 is elastically deformed substantially
uniformly, and local large deformation does not occur. Thus, the
contact member 2009 abuts on the outer circumferential surface of
the application roller 1001 consecutively with no space
therebetween, and can create the substantially closed space, as
shown in FIGS. 6 to 8.
On the other hand, as shown in FIGS. 3 to 5, the space creating
base 2002 is provided with a liquid supply port 2004 and a liquid
collection port 2005 in the region surrounded by the contact member
2009, each port being formed by making a hole penetrating the space
creating base 2002. These ports communicate with cylindrical joint
portions 20041 and 20051, respectively, which are provided on a
back side of the space creating base in a protruding manner. The
joint portions 20041 and 20051 are in turn connected to the
below-described liquid channel 3000. In this embodiment, the liquid
supply port 2004 is formed near one end portion (the left end
portion in FIG. 3) of the region surrounded by the contact member
2009, and the liquid collection port 2005 is provided near the
other end portion (the right end portion in FIG. 3) of the same
region. The liquid supply port and the liquid collection port are
not limited by the above configuration, and may be formed at any
location in the space creating base. In addition, the number of the
liquid supply ports and the number of the liquid collection ports
may be arbitrary. The liquid supply port 2004 is used to supply, to
the above-described liquid retention space S, the application
liquid supplied from the liquid channel 3000. The liquid collection
port 2005 is used to allow the liquid in the liquid retention space
S to flow out to the liquid channel 3000. By supplying the liquid
and allowing the liquid to flow out, the application liquid is
caused to flow from the left end portion to the right end portion
in the liquid retention space S.
(Application Liquid Channel)
FIG. 11 is an explanatory diagram showing a schematic configuration
of the liquid channel 3000 connected to the liquid retention member
2001 of the application liquid supply means.
The liquid channel 3000 has a first channel 3001 which connects the
liquid supply port 2004 of the space creating base 2002 being an
element of the liquid retention member 2001, and a storage tank
3003 storing the application liquid. In addition, the liquid
channel 3000 has a second channel 3002 which connects the liquid
collection port 2005 of the space creating base 2002 and the
storage tank 3003. This storage tank 3003 is provided with an
atmosphere communication port 3004, and the atmosphere
communication port is provided with an atmosphere communication
valve 3005 switching between an atmosphere communicating state and
an atmosphere isolation state. The atmosphere communication port
3004 preferably has a labyrinth structure in order to suppress
vaporization. In addition, a switching valve 3006 is provided in
the first channel 3001, making it possible to switch between the
state where the first channel 3001 and the atmosphere communicate
with each other and the state where these are isolated from each
other. In the second channel 3002, a pump 3007 is connected, which
is used to force the application liquid and air to flow in a
desired direction in the liquid channel 3000.
In this embodiment, the first and second channels 3001 and 3002 are
formed of circular tubes. Openings formed at respective ends of the
tubes are located at or near the bottom of the storage tank 3003,
so that the application liquid in the storage tank 3003 can be
completely consumed.
The pump 3007 in this embodiment is constituted of a tube pump as
shown in FIG. 19. The tube pump 3007 includes a rotor 30071 rotated
by a pump drive motor (not shown) and a pump forming tube 30072
having flexibility, which is disposed in an arc shape along the
periphery of the rotor 30071. In addition, the tube pump 3007 has
two rollers 30073 and 30074 freely rotatably supported by the rotor
30071. In this tube pump, when the rotor 30071 rotates, at least
one of the rollers 30073 and 30074 rolls while squeezing the pump
forming tube 30072. This rolling movement causes the application
liquid or air in the pump forming tube 30072 to be fed to the
downstream side (to the storage-tank side tube 30022 in FIG. 12),
and, at the same time, causes the application liquid or air to be
sucked from the liquid-retention-member side tube 30021. While the
tube pump 3007 is stopped, the pump forming tube is always in a
squeezed state, and the communication between the tubes 30021 and
30022 is blocked.
For the switching valve 3006 in this embodiment, various kinds of
valves can be used as long as the valve can switch between the
state where the first channel 3001 and the atmosphere communicate
with each other and the state where these are isolated from each
other. In this embodiment, however, a three-way valve as shown in
FIG. 11 is used. The three-way valve 3006 has three ports
communicating with each other. The three-way valve 3006 is made
capable of selectively causing two of these ports to communicate
respectively with two of a storage-tank side tube 3011, a
liquid-retention-member side tube 3012 and an atmosphere
communication port 3013 in the first channel 3001. The switching of
this three-way valve 3006 allows for the selective switching
between a connection state where the tubes 3011 and 3012 are
allowed to communicate with each other and a connection state where
the tube 3012 and the atmosphere communication port 3013 are
allowed to communicate with each other. In this way, it is made
possible to selectively supply, to the liquid retention space S
created by the liquid retention member 2001 and the application
roller 1001, the application liquid in the storage tank 3003 or the
air taken in from the atmosphere communication port 3013.
Specifically, when the tubes 3011 and 3012 communicate with each
other as shown in FIG. 13, the application liquid in the storage
tank 3003 will be supplied to the liquid retention space S. On the
other hand, when the tube 3012 and the atmosphere communication
port 3013 communicate with each other as shown in FIG. 14, the air
taken in from the atmosphere communication port 3013 is supplied to
the liquid retention space S. The switching of the three-way valve
3006 is performed in accordance with a control signal from a
below-described control unit 4000, so that the filling or the
supply of the application liquid is performed.
(Control System)
FIG. 12 is a block diagram showing a schematic configuration of a
control system in the liquid application device of this
embodiment.
In FIG. 12, reference numeral 4000 denotes a control unit as
control means for controlling the whole liquid application device.
This control unit 4000 includes: a CPU 4001 which performs various
processing, such as computation, control, and discrimination; and a
ROM 4002 which stores a control program and the like, which are
executed by this CPU 4001, for processes and the like described
later in connection with FIG. 13. Additionally, the control unit
4000 further includes: a RAM 4003 which temporarily stores input
data and data on which the CPU 4001 is performing processing; and a
nonvolatile memory 4013 such as a flash memory or an SRAM.
The control unit 4000 has the functions of: obtaining information
indicating lapse of time after the previous liquid flowing
operation (the previous circulating operation) which will be
described later; and, based on this information indicating the
lapse of time after the previous liquid flowing operation,
controlling a preliminary circulation performed by liquid moving
means (a pump).
Additionally, an input operation unit 4004 and a display unit 4005
are connected to the control unit 4000. The input operation unit
4004 includes a keyboard with which predetermined commands, data
and the like are inputted, or various switches. The display unit
4005 displays various pieces of information such as input and
setting of the liquid application device. In addition, a detection
unit 4006 including a sensor for detecting the position of an
application medium, the operation condition of each portion, or the
like, and a timer system 4012 having a built-in battery are
connected to the control unit 4000. Moreover, the roller drive
motor 1004, a pump drive motor 4009, the atmosphere communication
valve 3005 and the switching valve 3006 are connected to the
control unit 4000 via drive circuits 4007, 4008, 4010 and 4011,
respectively. It should be noted that the sensors constituting the
detection unit 4006 include a liquid detecting sensor, and a
temperature detecting sensor in the second embodiment.
In this embodiment, with the use of the above configuration, during
an application operation (a liquid application operation) in which
the application liquid is applied to application media, the stop
and the activation (driving) of the pump 3007 are controlled in
accordance with predetermined timing.
(Liquid Application Operation Sequence)
FIG. 13 is a flow chart showing a procedure relating to the liquid
application by the liquid application device of this embodiment.
Description will be given below of each step relating to the liquid
application with reference to this flow chart. Once the liquid
application device is turned on, the control unit 4000 carries out
the following application operation sequence in accordance with the
flow chart shown in FIG. 13.
Preliminary Circulation Step
In step S1, a later described preliminary circulation step is
performed on each one of the following portions (hereinafter,
referred to only as "the portions"): the liquid retention space S,
the respective channels 3001 and 3002, the three-way valve 3006,
and the pump 3007. The preliminary circulation step is performed
regardless of whether or not the application liquid has been filled
in the portions. A preliminary circulation sequence of this
preliminary circulation step is performed by driving the pump 3007
for a certain period of time while opening the atmosphere
communication valve 3005 of the storage tank 3003 to the
atmosphere.
Note that, in a case where the application liquid has already been
filled in the portions, it is only necessary to circulate the
liquid in a flow channel including a route from the channel 3001 to
the liquid retention space S, then to the channel 3002, and then to
the storage tank 3003. On the other hand, in a case where the
application liquid has not been filled in the portions, the liquid
is filled in the portions while the liquid is circulated in the
flow channel including the route from the channel 3001 to the
liquid retention space S, then to the channel 3002, and then to the
storage tank 3003.
This preliminary circulation may be performed while rotating the
application roller, or performed with the application roller
stopped. It might be preferable to rotate the application roller,
in order to remove matter increased in the viscosity fixedly
attached at the contact area of the liquid retention member with
the application roller.
Note that "application liquid relating to the preliminary
circulation" refers to application liquid actually circulated in
the portions during the preliminary circulation step. Additionally,
in a case where the thickened matter and/or stuck matter are
miscible with the application liquid used in the preliminary
circulation, the application liquid relating to the preliminary
circulation includes the miscible matter mixed with the liquid.
Application Steps
After the preliminary circulation has been finished in step S1, the
application roller 1001 starts to rotate clockwise as shown by the
arrow in FIG. 1 (step S2). With this rotation of the application
roller 1001, the application liquid L filled into the liquid
retention space S overcomes the pressing force of the contact
member 2009 of the liquid retention member 2001 against the
application roller 1001, and passes through the interface between
the application roller 1001 and a lower edge portion 2011 of the
contact member 2009. This application liquid L having passed
through the interface adheres to the outer circumferential surface
of the application roller 1001 forming a layer. The application
liquid L adhering to the application roller 1001 is sent to a
contact portion between the application roller 1001 and the counter
roller 1002.
Subsequently, the application medium feeding mechanism 1006
transfers an application medium to the nip area between the
application roller 1001 and the counter roller 1002, allowing the
application medium to be inserted between these rollers. This
inserted application medium is then transferred toward the delivery
unit as the application roller 1001 and the counter roller 1002
rotate (step S3). During this transfer, the application liquid
applied to the outer circumferential surface of the application
roller 1001 is transferred from the application roller 1001 to the
application medium P as shown in FIG. 9. Note that, needless to
say, the means for feeding the application medium to the interface
between the application roller 1001 and the counter roller 1002 is
not limited to the above feeding mechanism. Any means can be used.
For example, manual feeding means accessorily utilizing a
predetermined guide member may be additionally used, or the manual
feeding means may be used singly.
In FIG. 9, the cross hatched part indicates the application liquid
L. It should be note that, in this figure, the thicknesses of the
layers of the application liquid on the application roller 1001 and
the application medium P is depicted relatively larger than the
actual thickness, for the purpose of the clear illustration of the
state of the application liquid L shown at the time of the
application.
In this way, the part of an application medium P to which the
liquid has been applied is transferred in the direction indicated
by the arrow by the transferring force of the application roller
1001, and, at the same time, the part of the application medium P
to which the liquid is not applied is transferred to the contact
area between the application medium P and the application roller
1001. By performing this operation continuously or intermittently,
the application liquid is applied to the entire surface of the
application medium.
Incidentally, FIG. 9 shows an ideal state of application where all
the application liquid L, which has passed the contact member 2009
and has stuck to the application roller 1001, has been transferred
to the application medium P. In fact, however, all the application
liquid L having stuck to the application roller 1001 is not always
transferred to the application medium P. Specifically, in many
cases, when the transferred application medium P moves away from
the application roller 1001, the application liquid L also sticks
to the application roller 1001, and thus remains on the application
roller 1001. The remaining amount of the application liquid L on
the application roller 1001 varies depending on the material of the
application medium P and the microscopic irregularities of the
surface. In a case where the application medium is a plain paper,
the application liquid L remains on the circumferential surface of
the application roller 1001 after the application operation.
FIGS. 24 to 26 are explanatory diagrams for explaining an
application process proceeding between the application surface and
the surface of the medium in a case where the medium P is a plain
paper. In these figures, the liquid is expressed by the regions
filled in with black.
FIG. 24 shows a state of the application roller 1001 and the
counter roller 1002 in an area upstream of the nip area thereof. In
this figure, the liquid has stuck to the application surface of the
application roller 1001 in such a manner that the liquid thinly
covers the microscopic irregularities of the application
surface.
FIG. 25 shows a state of both of the surface of the plain paper,
which is the medium P, and the application surface of the
application roller 1001 in the nip area of the application roller
1001 and the counter roller 1002. In this figure, the convex
portions of the surface of the plain paper, which is the medium P,
abuts on the application surface of the application roller 1001,
and, from the abutting portions, the liquid instantly permeates
into or sticks on the surface fibers of the plain paper, which is
the medium P. The liquid which has stuck to the part of the
application surface of the application roller 1001, which part does
not abut on the convex portions of the surface of the plain paper,
remains on the application surface of the application roller
1001.
FIG. 26 shows a state of the application roller 1001 and the
counter roller 1002 in an area downstream of the nip area thereof.
This figure shows a state where the medium and the application
surface of the application roller 1001 have been completely
separated from each other. The liquid sticking to those parts of
the applying surface of the application roller 1001 which do not
contact with the convex portions on the surface of the plain paper
remains on the applying surface. The liquid on the contacting parts
also remains with very small amount on the application surface.
The application liquid remaining on the application roller 1001
overcomes the pressing force of the contact member 2009 of the
liquid retention member 2001 against the application roller 1001,
passes through the interface between the application roller 1001
and an upper edge portion 2010 of the contact member 2009, and is
brought back into the liquid retention space S. The returned
application liquid is mixed with the application liquid filled in
the liquid retention space S.
As shown in FIG. 10, also in a case where the application roller
1001 is rotated when there is no application medium, the returning
operation of the application liquid is similarly performed.
Specifically, the application liquid stuck to the circumferential
surface of the application roller 1001 by rotating the application
roller 1001 passes through the interface of the contact area
between the application roller 1001 and the counter roller 1002.
After this, the application liquid is distributed between the
application roller 1001 and the counter roller 1002, and remains on
the application roller 1001. The application liquid L sticking to
the application roller 1001 passes through the interface between
the upper edge portion 2010 of the contact member 2009 and the
application roller 1001, enters the liquid retention space S, and
is mixed with the application liquid filled in the liquid retention
space S.
Finishing Steps
Once the application operation to the application medium is
performed as described above, the determination as to whether or
not the application step may be finished is made (step S4). If the
application step may not be finished, the flow retunes to step S3,
and the application operation is repeated until the application
step is completed on all the area that requires the application of
the application medium. On the other hand, after the application
step is finished in step S4, the application roller 1001 is stopped
(step S5). Thereafter, post-processing, which includes a collection
operation for collecting the application liquid in the application
space S and the liquid channel, is performed (step 6). Here, the
processing relating to the application is ended.
Note that the above collection operation is performed in a manner
that, by opening the atmosphere communication valves 3005 and the
switching valve 3006, and additionally driving the pump 3007, the
application liquid in the liquid retention space S and the second
channel 3002 is caused to flow into the liquid storage tank 3003.
By carrying out this collection operation, vaporization of the
application liquid from the liquid retention space S can be
reduced. Additionally, after the collection operation, the
atmosphere communication valve 3005 is closed, and the
communication between the first channel 3001 and the atmosphere
communication port 3013 is blocked by switching the switching valve
3006, so that the storage tank 3003 is cut off from the atmosphere.
As a result, while the vaporization of the application liquid from
the storage tank 3003 can be reduced, the flowing-out of the
application liquid can be at least reduced or completely prevented
even if the device is inclined during the transferring or the
carrying thereof.
Once the post-processing in step S6 is finished, information on the
time when the post-processing is finished is stored. Here, the time
when the post-processing is finished is a time when the pomp is
stopped. That is, when the post-processing is finished, the CPU
4001 reads from the timer system 4012, and stores, in the
nonvolatile memory 4013, information on the time when the above
collection operation, that is, the latest liquid flowing operation
(circulation operation), is finished. Since the timer system 4012
has the built-in battery, it can perform timing by receiving a
power supply from the above built-in battery, even after the power
supply thereof has been stopped.
Note that the time when the above collection operation is finished
may be a clock time, or may be a lapse of time after a certain
reference point (difference of times).
As has been described above, in the liquid application device in
this embodiment, with the rotation of the application roller 1001,
the application liquid filled into the liquid retention space S
overcomes the pressing force of the lower edge portion 2011 of the
contact member 2009 against the application roller 1001, and passes
through to the outside of the liquid retention space S. This
application liquid having passed through to the outside is supplied
to the outer circumferential surface of the application roller 1001
forming a layer. The thickness of this application liquid, i.e.,
the amount of the application liquid supplied to the application
roller 1001 depends on: viscosity of the application liquid; the
relative speed between the outer circumferential surface of the
application roller 1001, and the medium; the pressing force of the
contact member 2009 against the outer circumferential surface of
the application roller 1001; and the like.
In this embodiment, a preliminary circulation is performed in order
to remove the harmful effects derived from the vaporization of the
liquid. Here, when the liquid vaporizes in this embodiment will be
described. Joining portions among the respective parts used in this
embodiment, and tubes used for the respective channels 3001 and
3002, cannot perfectly keep air in a hermetically sealed state.
Consequently, the liquid vaporizes from those parts although the
vaporization progresses very little by little. For example, during
a period between the filling operation by the preliminary
circulation step, and the collection operation by the
post-processing step, the application liquid (reactor) in each of
the channels 3001 and 3002 is increasingly thickening. When the
liquid has thickened, it turns into a pasty state (also referred to
as a thickened matter), or generates a solid matter (also referred
to as a sticking matter) resulting from solidification of the
liquid. The liquid having turned into the pasty state has a high
viscosity than the liquid in a normal state, thereby becoming a
factor in hindering flow of the liquid in the channels when the
liquid is filled therein next time.
Additionally, in some occasions, the liquid left uncollected in the
post-processing remains in the channels 3001 and 3002 each having a
complicated mechanism. The liquid thus remaining in an internal
supply path or in the pump undergoes vaporization until the liquid
is filled by the filling operation in a subsequent preliminary
circulation step. The liquid in a pasty state hinders the flowing
of the liquid when the liquid is filled again. Moreover, if the
thickened liquid exists in the nip area between the application
roller 1001 and the counter roller 1002, differences are generated
in thickness of the liquid which passes through the above nip area.
Thereby, application nonuniformity is caused.
Note that, in this Description, "thickening of liquid" means that
the viscosity of the liquid with a predetermined composition
existing in the parts other than the liquid storage tank becomes
higher than the viscosity of the liquid contained in the liquid
holding tank as a result of including substances, as in pasty, gel,
solid and other states, whose viscosities become higher than the
liquid through evaporation of a solvent, water or the like from the
liquid with the predetermined composition. "Thickening of liquid"
further means a state where the viscosity of the liquid is made
higher by the reduction in temperature, and a state, derived from a
difference in coagulation point, where one of the components of the
liquid, each of which has a different coagulation point from those
of others, is coagulated around the coagulation point of the
component. That is, "thickening of liquid" implies that, on
sidewalls of a collection path and the supply path, inside the
switching valve, on a sidewall of the liquid retention member,
inside the pump, and the like, the liquid turns into a state where
the liquid becomes difficult to flow in the above passages.
Additionally, "thickened liquid" includes: a state where at least
any one of the thickened matter and the sticking matter is
dispersed in the liquid; and a state where the liquid, and at least
any one of the thickened matter and the sticking matter, are
phase-separated.
While the "thickened matter" indicates one formed of the liquid
thickened and turned into the pasty or gel state, and the "sticking
matter" indicates one with a viscosity further increased from the
viscosity of a thickened matter. That is, the thickened matter and
the sticking matter both perform the function of hindering the flow
of the liquid by, for example, blocking at least part of the each
passage, and these matters are products formed of the liquid and
having a higher viscosity than the liquid.
The thickened matter and the sticking matter become mixed with the
liquid when they have been blended together for a certain length of
time after the refilling of the liquid. With this property taken
into account, the harmful effects of the thickening of the
application liquid caused by the vaporization are avoided in this
embodiment by performing the preliminary circulation in accordance
with the lapse of time after the previous liquid flowing operation
(also referred to as the "latest circulation operation"). The
preliminary circulation operation is a circulation operation having
a purpose different from purposes of the conventional filling
operation, the circulation operation performed in each of, or
between the application operations, and the collection operation.
That is, the preliminary circulation is a circulation for making
the viscosity of the application liquid, which has thickened due to
generation of the thickened matter and the sticking matter, lower
than the viscosities of the thickened matter and the sticking
matter. In a conventional sequence from filling, to printing
(application), and then to finishing, it is essential to supply a
desired amount of the application liquid, and circulation of the
liquid for that purpose is imperative. However, a sequence of the
preliminary circulation in this embodiment is a circulation of the
application liquid, performed for the purpose of maintaining
reliability of the application liquid and thereby maintaining image
quality of the prints. By circulating the application liquid, the
preliminary circulation performs the functions of: mixing the
thickened matter with the application liquid; and lowering the
concentration of the application liquid having thickened, using the
liquid before thickening.
Note that, in this Description, the "circulation operation"
includes: a circulation operation for filling the application
liquid into the liquid retention space S, the respective channels
3001 and 3002, the three-way valve 3006 and the pump 3007; and a
circulation operation for collecting the application liquid to the
ink storage tank 3003. The "circulation operation" also includes: a
circulation operation performed during the application operation;
circulation operations performed between operations of the filling,
of the application and of the collection; and the preliminary
circulation operation. Therefore, the latest circulation operation
indicates the one precedes the current circulation operation in
question.
In the present invention, the preliminary circulation of the
application liquid is performed in accordance with the lapse of
time after the previous circulation operation (the latest
circulation operation), in order to reduce hindrance to the
circulation of the application liquid, and also to reduce the
application nonuniformity, which are derived from the thickened
application liquid as has been described above.
FIG. 14 is a flow chart showing a procedure relating to the
preliminary circulation step corresponding to step S1 of FIG.
13.
First of all, in step S21, the CPU 4001 obtains information
concerning the lapse of time after the previous liquid flowing
operation (previous circulation operation). That is, once an
application start command is inputted, information indicating a
current clock time is read out from the timer system 4012.
Information indicating a time when the previous liquid flowing
operation (the previous circulation operation) has been finished is
also read out, the information being stored in the nonvolatile
memory 4013. Then, the information indicating the lapse of time
after the previous circulation operation is obtained based on these
two pieces of information having been read out.
Subsequently in step S22, the CPU 4001 determines a preliminary
circulation sequence based on the information indicating the lapse
of time obtained in step S21. Finally in step S23, the preliminary
circulation sequence is performed based on the preliminary
circulation sequence determined in step S22.
The preliminary circulation sequence is determined in step S22
based on the lapse of time after the previous circulation
operation. One example of a method for the determination is shown
in FIG. 15. By referring to a table as shown in FIG. 15, the
preliminary circulation sequence corresponding to the lapse of time
after the previous circulation operation is determined.
Specifically, any one of preliminary circulation sequences A to F
is selected, the one corresponding to the time interval into which
the obtained lapse of time falls, among predetermined time
intervals P1 to P6 shown in FIG. 15 where 0.ltoreq.P1
(seconds)<P2 (seconds), P2 (seconds).ltoreq.P3 (seconds)<P4
(seconds), P3 (seconds).ltoreq.P4 (seconds)<P5 (seconds), and P4
(seconds).ltoreq.P5 (seconds)<P6 (seconds).
These preliminary circulation sequences A to F are made different
in circulation speed of the liquid. The longer the lapse of time
after the previous circulation operation is, the higher the
probability of having the application liquid sticking to passage
walls becomes. In order to separate this sticking matter off from
the passage walls, it is desired that the circulation speed of the
liquid be made faster. Therefore, the circulation speeds of the
liquid for the respective preliminary sequences are set faster with
increasing length of the lapse of time. That is, the circulation
speeds of the respective sequence are set beforehand in the order
of "A<B<C<D<E<F".
Additionally, the preliminary circulation sequences A to F are not
limited to the ones made different in circulation speed of the
liquid. For example, they may be the ones made different in
circulation period of the liquid. That is, the longer the
circulation period of the liquid is, the more thickened matter and
sticking matter, remaining in the flow channel, are mixed with the
liquid currently circulating. In this regard, the circulation
periods of the liquid is set longer with increasing length of the
lapse of time. That is, the liquid circulation periods of the
respective sequence are set beforehand in the order of
"A<B<C<D<E<F".
Furthermore, the preliminary circulation sequences A to F may be
the ones made different both in circulation speed of the liquid,
and in circulation period of the liquid.
Thus in this embodiment, based on the lapse of time after the
previous circulation operation, one preliminary circulation
sequence is selected from among the different preliminary sequences
of plural variations. Thereby, the preliminary circulation sequence
comes to be selected in consideration of the lapse of time on which
the thickening of the application liquid depends. Accordingly, the
preliminary circulation matched with a degree of the thickening of
the application liquid becomes possible. The method where the
circulation speeds and the circulation periods in the respective
preliminary circulation sequences A to F are made different can be
realized, by controlling a rotation speed and a rotation period of
the pump 3007, as shown in FIG. 16 for example. Since each of the
preliminary circulation sequences A to F is set by changing the
rotation speed and the rotation period of the pump 3007 as shown in
FIG. 16, the amount of the application liquid used for the
preliminary circulation can be optimized based on the obtained
lapse of time. Therefore, unnecessary performance of the
preliminary circulation is eliminated, whereby a cost decrease is
also brought about.
As has been described above, according to this embodiment, even in
a case where the application liquid in each of the portions has
thickened or stuck due to the longer lapse of time after the
previous circulation operation or the like, it becomes possible to
smoothly perform a circulation of the application liquid into the
liquid retention space from the storage tank without adding a
large-scale device. Additionally, the thickening and sticking of
the application liquid in each of the portions can be reduced. As a
result, while quality of the application liquid can be maintained,
the nonuniformity of application can be reduced. For this reason,
the application of the application liquid to a medium always
becomes uniform, a high-quality image always can be formed, and
reliability of images can be maintained.
In particular, it becomes possible to reduce the viscosity of the
application liquid having thickened or stuck by not being taken
care of in each of the portions for a long time period, by
performing the preliminary circulation sequence according to the
lapse of tie after the previous circulation operation. More
specifically, it becomes possible to make the viscosity of the
application liquid in question closer to the viscosity of the
application liquid stored in the storage tank.
Second Embodiment
In the first embodiment, the optimum preliminary circulation
sequence is selected corresponding to the obtained lapse of time
after the previous circulation operation. In addition to this, the
optimum preliminary circulation sequence may be configured to be
selected corresponding to a state of each of the portions at the
start of the preliminary circulation after the lapse of time. In
this embodiment, the preliminary circulation sequence is determined
based not only on the lapse of time after the previous circulation
operation, but also on whether or not there is the application
liquid in the liquid retention space S at the start of the
preliminary circulation.
FIG. 17, which is a flow chart showing a procedure relating to a
preliminary circulation step according to the embodiment of the
present invention, is a flow chart showing a procedure relating a
preliminary circulation step corresponding to step S1 of FIG.
13.
In step S31, the CPU 4001 obtains information indicating the lapse
of time after the previous circulation operation. That is, once the
application start command is inputted, the CPU 4001 reads out
information indicating the current clock time from the timer system
4012. Additionally, the CPU 4001 reads out information indicating
the time when the previous circulation operation has been finished,
the information being stored in the nonvolatile memory 4013. Then,
the information indicating the lapse of time after the previous
circulation operation is obtained based on these two pieces of
information having been read out. Subsequently in step S32,
judgment as to whether the application liquid is filled in the
liquid retention space S is made by using a liquid detection sensor
provided inside the liquid retention space S. In a case where the
application liquid is filled in the liquid retention space S, the
procedure advances to step S33. In step S33, a table 1 which is the
table corresponding to cases where the application liquid is filled
is selected, for example, in FIG. 18. On the basis of this, in step
S34, by referring to FIG. 18, a preliminary circulation sequence is
determined based on the lapse of time after the previous
circulation operation. Subsequently, in step S35, the preliminary
circulation sequence selected in step S34 is carried out.
In a case where it has been judged that the application liquid is
not filled in the liquid retention space S, the procedure advances
to step S36. In step S36, a table 2 which is the table
corresponding to cases where the application liquid has is not
filled is selected. On the basis of this, in step S37, by referring
to FIG. 18, a preliminary circulation sequence is determined based
on the lapse of time after the previous circulation operation.
Subsequently, in step S35, the preliminary circulation sequence
selected in step S37 is carried out.
As shown in FIG. 18, the tables for determining the preliminary
sequence are configured to make it possible to select the optimum
sequence based both on the lapse of time after the previous
circulation operation, and on the situation with respect to
presence or the absence of the application liquid inside the liquid
retention space S. That is, the optimal preliminary circulation
sequence is selected based both on a time interval, into which the
obtained lapse of time falls, among predetermined time intervals
P11 to P13, and on with whether or not the application liquid is
filled inside the liquid retention space S. Here, the time interval
P11 is expressed as "0<the lapse of time.ltoreq.the upper limit
value of the time interval P11". Additionally, the time interval
P12 is expressed as "the upper limit value of the time interval
P11<the lapse of time.ltoreq.the upper limit value of the time
interval P12". Moreover, the time interval P13 is expressed as "the
upper limit value of the time interval P12<the lapse of
time".
Note that, although this embodiment assumes a configuration where
the lapse of time after the previous circulation operation and the
presence or absence of the application liquid inside the liquid
retention space S are used as the factors in determining the
optimum preliminary circulation sequence, the present invention is
not limited by this configuration. For example, the optimum
preliminary circulation sequence may be configured to be determined
based both on the lapse of time after the previous preliminary
circulation, and on the temperature of the device. In this case, by
configuring a temperature detection sensor provided inside the
device to detect the temperature of the device, the preliminary
circulation sequence may be selected based on the detected
temperature.
On the other hand, while judgment on whether the application liquid
is filled in the liquid retention space S is made by using the
liquid detection sensor, the liquid detection sensor may be
unnecessary in a case where this judgment can be made by using a
manner other than the above.
Other Embodiments
Note that, in each of the above embodiments, the amount of the
liquid that should be applied to the medium can be changed by
changing the pressing force of the liquid retention member against
the application roller by changing the elastic force of the spring
member. Furthermore, the amount of the liquid that should be
applied can be changed also by changing degrees of hardness of the
liquid retention member, of the application roller, a roller
supporting an endless belt, and the like.
Additionally, although the case where a coil spring as the spring
member is used as the pressing means for pressing the liquid
retention member against the application roller has been presented
in each embodiment, the present invention is not limited by the
case. As the above pressing means, another type of spring, for
example, a plate spring can be used. Furthermore, an elastic
material member such as the one of rubber can be used in stead of
the spring member.
Moreover, numbers and forming positions of the liquid supply ports
and the liquid collection ports formed in the liquid retention
member are not limited by the above embodiments. For example, with
the liquid supply ports being arranged in both end portions of the
inside of the liquid retention space, at least one liquid
collection port may be arranged between the liquid supply ports.
Alternatively, with the liquid collection ports arranged in both
end portions of the inside of the liquid retention space, at least
one liquid supply port may be arranged between the liquid
collection ports. What is essential here is that the liquid
retained inside the liquid supply member is capable of flowing in
the liquid retention space.
Furthermore, although the case where the counter roller is provided
so as to face the application roller or the endless belt has been
presented in each of the above embodiments, the present invention
is not limited by the case. That is, a transferring force of the
application roller or the endless belt is allowed to be conveyed to
the medium by providing, instead of the counter roller, a
supporting member formed of a plate material or the like, and by
configuring an application member to be held between this plate
material and the application roller. In this case, it is necessary
that a surface of the supporting member, by which it makes contact
with the medium, be configured to be a surface having a low
friction coefficient, and a small surface energy.
(Embodiment of an Inkjet Recording Apparatus)
The liquid application devices shown in the first and second
embodiments are effective when applied to inkjet recording
apparatuses. Description will be given below of the case where the
liquid application device described above is applied to an inkjet
recording apparatus. However, since the application operation
control described in connection with the first and second
embodiments is applied similarly, the description thereof will be
omitted.
FIG. 20 is a diagram showing a schematic configuration of the
inkjet recording apparatus 1 including the application mechanism
having almost the same configuration as that of the above liquid
application device.
In the inkjet recording apparatus 1, provided is a feed tray 2 on
which a plurality of recording media P are stacked, and a semi
lunar shaped separation roller 3 separates the recording media P
stacked on the feed tray one by one, and feeds each medium to a
transfer path. In the transfer path, the application roller 1001
and the counter roller 1002 constituting the liquid application
means of the liquid application mechanism are disposed. The
recording medium P fed from the feed tray 2 is transferred to the
interface between the rollers 1001 and 1002. The application roller
1001 is caused to rotate clockwise in FIG. 20 by the rotation of
the roller drive motor, and applies the application liquid on the
recording surface of the recording medium P while transferring the
recording medium P. The recording medium P to which the application
liquid has been applied is sent to the interface between a transfer
roller 4 and a pinch roller 5. Subsequently, the counterclockwise
(in this figure) rotation of the transfer roller 4 transfers the
recording medium P on a platen 6, and moves the medium to a
position facing a recording head 7 being an element of recording
means. The recording head 7 is an inkjet recording head in which
the predetermined number of nozzles for ejecting ink are arranged.
While the recording head 7 scans the recording surface in a
direction perpendicular to the plane of the drawing sheet, ink
droplets are ejected from the nozzles to the recording surface of
the recording medium P in accordance with the recorded data to
perform recording. An image is formed on the recording medium while
the recording operation and the transfer operation by a
predetermined feed carried out by the transfer roller 4 are
alternately repeated. With the image forming operation, the
recording medium P is held between a sheet discharging roller 8 and
a sheet discharging spur roller 9 provided downstream of the
scanning region of the recording head in the transfer path of the
recording media, and is discharged onto a sheet discharged tray 10
by the rotation of the sheet discharging roller 8.
As the inkjet recording apparatus, a so-called full-line type
inkjet recording apparatus can be constructed, which performs the
recording operation by using a long recording head which has
ink-discharging nozzles arranged across the maximum width of the
recording media.
The application liquid used in this embodiment is a treatment
liquid for promoting the coagulation of pigment when the recording
is carried out using an ink which contains pigment as a coloring
material. With regard to this embodiment, the treatment liquid is
used as the application liquid, so that the treatment liquid is
allowed to react with the pigment as a coloring material in the ink
ejected to the recording medium, to which the treatment liquid has
been applied, to promote the coagulation of pigment. By this
insolubility, it is made possible to achieve the improvement of the
recording density. In addition, it is also made possible to reduce
or prevent bleeding. Needless to say, the application liquid used
in the inkjet recording apparatus is not limited to the above
example.
FIG. 21 is a perspective view showing a main part of the
above-described inkjet recording apparatus. As shown in this
figure, an application mechanism 100 is provided above an edge of
the feed tray 2, and the recording means including the recording
head 7 is provided above the application mechanism and over a
middle portion of the feed tray 2.
FIG. 27 is a block diagram showing a control system of the
above-described inkjet recording apparatus. In this figure, the
roller drive motor 1004, the pump drive motor 4009, and the
atmosphere communication valve 3005, which are elements of the
liquid application mechanism, are the same elements as those
described in connection with the above liquid application
device.
A CPU 5001 controls the driving of each element of the application
mechanism in accordance with the program of a procedure described
later in connection with FIG. 28. The CPU 5001 also controls the
driving of an LF motor 5013, a CR motor 5015 and the recording head
7, which are included in the recording means, via drive circuits
5012, 5014 and 5016, respectively. Specifically, the transfer
roller 4, for example, is rotated by the driving of the LF motor
5013, and a carriage on which the recording head 7 is mounted is
moved by the driving of the CR motor. The CPU 5001 also effects
control of the ink discharge from the nozzles of the recording
head.
FIG. 28 is a flow chart showing a procedure of the liquid
application operation and the accompanying recording operation
using the inkjet recording apparatus of this embodiment. In this
figure, the processes in steps S101, S102, S104 to S106, and steps
S109 to S112 are the same as those in steps S1, S2, S4 to S6, and
steps S8 to S11, respectively, shown in FIG. 13.
As shown in FIG. 28, in this embodiment, when a command to start
the recording is inputted in the recording apparatus, processing of
the preliminary circulation is performed (step S101), and a series
of steps of the liquid application operation, which include
rotation of the application roller, are performed (steps S102 and
S103). Thereafter, the liquid is applied onto the recording
medium.
Onto the recording medium to which the application liquid has been
thus applied, the recording operation is performed (step S104).
Specifically, dots are formed in a manner that: the recording head
7 is caused to scan the recording medium P fed by a predetermined
amount each time by the transfer roller 4; and the ink is allowed
to adhere to the recording medium by ejecting the ink from the
nozzles based on the recorded data during this scanning. Since this
adhering ink reacts with the application liquid, it becomes
possible to improve density and to reduce bleeding. Recording onto
the recording medium P is performed by repeating the transfer of
the recording medium and the scanning of the recording head, and
the recording medium onto which the recording has been finished is
delivered onto the delivery tray 10. If it is judged in step S105
that the recording has been finished, the application roller is
stopped (S106), and post-processing including the collection
operation for collecting the application liquid inside the
application space Sand the liquid passages is performed (step
S7).
Once the post-processing in step S107 is finished, information
indicating a time when the post-processing has been finished is
stored. That is, once the post-processing is finished, the CPU 5001
reads out, from the timer system 5017, the information indicating a
time when the above collection operation corresponding to the
latest liquid flowing operation (circulation operation) is
finished. Then the CPU 5001 stores the information in the
nonvolatile memory 5018. Because the timer system 5017 has the
built-in battery, it can perform timing by receiving a power
supplied from the above built-in battery even after a power supply
of the apparatus has been stopped. By this step, the processing of
FIG. 28 is ended.
Although this embodiment assumes a configuration where the
recording operation is performed after the completion of
application of the application liquid onto one recording medium,
the present invention is not limited to this configuration. For
example, the present invention may assume a configuration where,
along with the liquid application onto a recording medium, printing
is sequentially performed onto parts for which the application has
been finished. That is, in a case where a length of the transfer
path reaching the recording head from the application roller is
shorter than a length of the recording medium, when a part of the
recording medium onto which part the liquid has been applied is
arrived at the scanning region of the recording head, the
application is performed onto another part of the recording medium
by the application mechanism. According to this configuration, the
liquid application and the recording are sequentially performed on
a part every time a predetermined amount of the recording medium is
transferred, and are repeated onto different parts on the recording
medium.
Additionally, in the recording apparatus of the present invention,
it is possible to improve the whiteness of the medium by applying a
liquid containing a fluorescent whitening agent to the recording
medium. In this case, the recording means used after the
application of the liquid is not limited to that of the inkjet
type. The effect can be obtained also by adopting the means of
other recording types, such as the thermal-transfer type and the
electrophotographic type.
In addition, as the application liquid, a photosensitizing agent
may be applied before recording in the recording apparatus of a
silver-halide photographic type.
While the present invention has been described with reference to
exemplary embodiments, it is to be understood that the invention is
not limited to the disclosed exemplary embodiments. The scope of
the following claims is to be accorded the broadest interpretation
so as to encompass all such modifications and equivalent structures
and functions.
This application claims the benefit of Japanese Patent Application
No. 2005-235403, filed Aug. 15, 2005, which is hereby incorporated
by reference herein in its entirety.
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